Process of producing benzanthrone carboxylic acid



Patented Feb. 12, 1935' UNITED STATES PATENT rnoonss OFPRODUCING BENZA'NTHRONE v CARBOXYLIO ACID Viktor M. Weinmayr, Milwaukee, and John M. Tinker, South Milwaukee, Wis., assignors to v E. I; 'du Pont de Nemours & Company, Wilmington, Del;,.a corporation of Delaware No Drawing, Applicationjsjcptember 19, 1932,

Serial No. 633,845"

This invention relates to the production ofother hand 'falling much below 80 0., and the organic compounds. Itisan object of our inmaintenance of the reactionat the 'elevatedtemven'tion to provide a process for the production perature for not-over 3' to 4 hours. v

I of benzanthrone-carboxylic acid. Other and Where a catalyst, such as copper, is used, the 5 further important objects of this invention will same temperature limits may be employed, but appear as the description proceeds. the time required for reaction much longer,

We have found that Bzl-benzanthrone-carsay 15-to 25 hours.- The "quantity of copper, on

' boxylic acid may be produced by reacting benthe other hand,is very much smallerthan in the zanthrone with carbon tetrachloride to give B'zlcase of. aluminum chloride, being. as usual, of

trichloromethyl-benzanthrone, and then hycatalyticmagnitude; that is, but afew per cent 10 drolyzing this product to the corresponding carof the weight of benzanthrone used. boxylic acid. It is our belief that the entering carbon atom The reaction between benzanthrone andcartakes the position Bz'l' in the benzanthrone bon tetrachloride may be efiected'by heating the molecule.

two substances together in anvexcess of the tet- 'O'ur invention thereforeconsists of a process rachloride andin the presence vof 'metal halide for. the manufacture ofa mixtureeoff benzane condensing agents or catalysts; A's condensing throne compounds of'the'general'formula: agents, anhydrous aluminum chloride, ferric C12 chloride or zinc chloride may be used. As cata- 1 lysts, copper, copper alloys, or copper compounds c are suitable. V i X I -Under more drastic conditions, two benzanthrone molecules enterinto reaction with each 1 molecule of carbon tetrachloride. The product v 1 is then B21, Bzli-dibenzanthrony1'-dichloro- I methane, which may be hydrolyzedto give di ll benzanthronyl-ketonel Such drastic conditions may in lud t us f excessive qu t t s o wherein X stands for a chlorine atom or a benaluml'num Chloride, the prolongation of the zanthron'e residue, and comprises furtherithe feareaction u til no further evolution of hydrotures "offirstregulating thereaction so as to 30 Chloric acid is Observedproduce substantial yieldsof the mon'obenzannd d r diti s. w ver. fo throne compound, and secondly, converting" the tan y y usi t v 1' mol of a u num reaction products by hydrolysis'into a' mixture of chloride per mol of benzanthrone, or by the use mpounds of the'general' formula:

of" copper or'a salt thereof as a catalyst, and in O I 35 either case'by stopping the reaction short of the period experimentally found'necessary for com- 0 plete reaction, considerable quantities of ben- 7 Under such mild conditions the reaction does not go to completion. Considerable quantities of unchanged benzanthrone are left over, andon the other hand, substantial quantities of dibenzanthrone-trichloro-methane are formed. a Y zanthronyl-dichloro-methane are formedasab'y- V I V I product We have found howeventhatby care wherein Y stands for the OH radical or for a 45 ful control of the conditions ofthe reaction, the" benzanthmne residue latter may be directedtoward t P 1 In the Flatter form the reaction products are benzanthrone-carboxyhc acid in sufiicient yield readily separable from each other as well to render the entire process of commercial infrom any unreacted material; Thus, thetalkanp terestmetalsalts'of benzanthrone carboxylic acid are 50 These optimumconditions for thecase where- Soluble, aqueous Solution, while diben'zam anhydrous aluminum chloride is dr thronyl-ketone and b'enzanthrone' itself are m be the use f n v r'l of alumlnum soluble; Hydrolysis of the reaction'mass, there! ride'per' mol ofbenzanthrone; thel'leating, at afore; bystheaid of alkali, converts thesam i t temperature not exceeding220 0., nor on'the di solution of an: alkali-metal salt'of rbe'nzan- Example 1 3000 parts of carbon tetrachloride, 460 parts of benzanthrone and 146 par'ts of anhydrous aluminum chloride are charged into an autoclave, and heated slowly to 180 C. The mass is maintained at 180-485 C. for 3 hours. During this period, hydrochloric acid is'evolved, and' the pressure continually rises. Thema'ss is now cooled and the pressure released, preferably by absorbing the hydrochloric acid in water. The mass is then discharged into 6000 parts of cold water and stirred for several hours to decompose the intermediate organic-aluminum chloridecomplex compound. The resulting suspension is filtered and washed with water. The excess carbon tetrachloride may be recoveredfrom the filtrate.

The light brown filter-cake is'suspended in 6000 parts of water, rendered alkaline with caus tic soda, and heated to 95-100 C. for several hours. The mass is now filtered, and the filtrate is acidified to precipitate Bzlebenzanthrone-car boxylic acid. The latter is filtered off and washed acid free.

The filter cake from the alkaline extraction mass contains unchanged benzanthrone and B21, Bzl'-dibenzanthronyl-ketone. To separate these, the filter cake is boiled in 3000 parts of toluene, cooled and filtered. The benzanthrone'is extracted and passes into the filtrate, while the ketone is insoluble and remains in the filter cake.

Example 2 are heated in a closed vessel to145- -150 C. for

about '4 hours. Themass is worked up as in Ex-v ample 1 and separated into Bzl-ben'zanthronecarboxylic acid, benzanthrone, and dibenzanthronyl-ketone.

Example 3 Example '4 I I 3000 parts of carbon tetrachloride, 460 parts of benzanthrone, and 4 parts of copper-bronze (metalliccopper in an exceedingly finely divided form) are heated in an autoclave to 160-165 C., for about 18 hours. The mass is cooled, the pressure is released, and the hydrochloric acid formed" The mass is then disis absorbed in water. charged into water and filtered. The filter cake is suspended" in water, rendered alkeline, and

further treated as in Example 1, to recover Bzlbenzanthrone-carboxylic acid.

Many variations are possible in our preferred procedure above indicated without departing from the spirit of this invention. For instance, the amount of carbon tetrachloride employed may be varied within wide limits. It will be noted that in addition to providing 1 mol of carbon tetrachloride for reaction with each mol of benzanthrone, we use an excess of the former to serve as a suspending medium for the entire mixture.

Consesquently, the minimum quantity of carbon tetrachloride employed is that which will H effect a thin, easily stirring suspension of the benzanthrone, as well as the inorganic constituents of the mixture. Beyond this, any quantity of carbon tetrachloride may be used.

'Instead of aluminum chloride, ferric chloride or zinc chloride may be used. Instead of copperbronze, copper powder orcopper compounds may beused' H.

The amount of aluminum chloride employed may be varied within reasonablelimits. However,

with increased quantitiesof aluminumchloride,

the proportion of dibenzanthronyl-dichloromethane formed in' the reaction'mass increases. It is therefore safer to keep the aluminum chloride-ben zanthrone ratio below 1 :l. A ratio er A, mol A1013 tol mol of benzanthrone appears to give the best results.

The reaction may take'place at higher or lower temperatures, as already indicated. Nor is pressure essential to the reaction, except in'so far as it'enables the use of higher temperatures, thereby increasing the-rate of reaction.-'

g Sodium or potassium chloride may be added to the aluminum-chloride to facilitate its melting at a lower temperature. r f I Y Although it is preferable to effect the hydrolysis bytheaid'of 'an'alkali in view of the resulting incidental separation of the benzanthrone car boxylic acid from the reaction mass, hydrolysis may nevertheless be effected by the aid. of an acid, say'dilute hydrochloric acid. In' this case, however, thebenzanthrone carboxylic' acid precipitates, together with the dibenzanthronyl-.

ketone, and further steps to separate these are requisite.

:Many other variations and modifications are possible within the scope of our invention, with out departing fromthe spirit thereof as defined by the subjoined claims.

It should be furtherunderstood thatvvhile' we, referred to the compounds produced,as.,.Bzl or 321,321, thereby expressingour belief as-to the most probable position of the entering" carbon, atom, ourinvention does not depend on any particular theory for operativeness. The following claims should therefore be construed as covering the processj herein described, regardless whether theresultant products are truly Bzlcom pounds or isomers thereof. 1 e r 1 Weclaim: 1. Alprocess for producing benzanthrone-car boxylic acid which comprises heating benzan throne with carbon tetrachloride to reaction tem-- peratures and under conditions-leading to their condensation, said conditions'being milder than those favoring the production of dibenza'nthronyl dichloro-methane, and hydrolyzing "the reaction product. l w

2. A process for producing be'nzanthrone-car boxylic acid which comprises heating benzanthrone with carbon tetrachloride to reaction'tem-- peratures and under-*conditions leading: to their condensation, ,said conditions being: milder: than those favoring. .the production of dibenzanthronyledi'chloro-methane, hydrolyzing the reaction product bythe aid. of: caustic alkali, and separating the alkali-metal salt of benzanthronecarboxylic acid from the by.-products of the reaction.

3..A;. process for producing Bzl-benzanthronecarboxylic acid. whichcomprises reacting benzanthrone with carbon tetrachloride in the, presence of a condensing agent for a period of time shorter than that required for complete reaction, whereby to produce a mixture of compounds represented by the general formula:

wherein X stands for a chlorine atom or for a benzanthrone radical, hydrolyzing the reaction mass by the aid of aqueous caustic alkali to produce a mixture of compounds represented by the general formula:

wherein Y stands for the OH radical or for a benzanthrone radical, and separating the aqueous solution of the alkali-metal salt of benzanthrone carboxylic acid from the residual, water-insoluble mass.

4. A process for producing benzanthrone-carboxylic acid which comprises heating benzanthrone with carbon tetrachloride in the presence of a metal halide condensing agent to reaction temperatures and under conditions leading to their condensation, said conditions being milder than those favoring the production of dibenzanthronyl-dichloromethane, and hydrolyzing the reaction product.

5. A process for producing benzanthrone-carboxylic acid which comprises reacting benzanthrone with carbon tetrachloride in the presence of a copper catalyst, dicontinuing the reaction before complete conversion into dibenzanthronyldichloromethane has taken place, and hydrolyzing the reaction product.

6. A process for producing benzanthronecarboxylic acid which comprises heating benzanthrone with carbon tetrachloride in the presence of anhydrous aluminum chloride to reaction temperatures and under conditions leading to their condensation, said conditions being milder than those favoring the production of dibenzanthronyldichloromethane, and hydrolyzing the reaction mass.

7. A process for producing benzanthrone-carboxylic acid which comprises reacting benzanthrone with carbon tetrachloride in the presence of copper-bronze discontinuing the reaction before complete conversion into dibenzanthronyldichloromethanehas taken place, andihydrolyz= ing'the reactionmass. 1 L

' '8. A process for'producing benzanthrone-marboxylic acidwhich comprises reacting 1 mol. of

benzanthrone withanexcess of carbon tetrachloride in the presence of not more than 1. mol of anhydrous aluminum chloride, discontinuing the reaction before completeconversion into diben-' zanthronyl-dichloromethane has taken place,'liydrolyzing the reaction product, and recovering Bzl-benzanthrone-carboxylic acid. I

9. A process for producing benzanthrone-carboxylic acid which comprises suspending benzanthrone in an excess of carbon tetracholoride and in the presence of not over 1 mol of anhydrous aluminum chloride, heating the mass to a temperature between 80 and 220 C., discharging the reaction mass into water, separating from the excess of carbon tetrachloride, adding sufficient causticalkali to render the mass alkaline, and separating the alkali-metal salt of benzanthrone-carboxylic acid.

10. A process for producing benzanthrone-carboxylic acid which comprises suspending benzanthrone in an excess of carbon tetrachloride and in the presence of substantially mol of anhydrous aluminum chloride, heating the mass to a temperature of about 145 to 180 C., and for a period not exceeding 4 hours, discharging the reaction mass into water, separating from the excess of carbon tetrachloride, adding sufiicient caustic alkali to render the mass alkaline, and separating the alkali-metal salt of benzanthronecarboxylic acid.

11. A process for producing benzanthrone-carboxylic acid which comprises suspending benzanthrone in an excess of carbon tetrachloride and in the presence of a small quantity of copper body, heating the mass to a temperature of 160 to 165 C. for a period of about 18 hours, discharging the reaction mass into water, separating from the excess of carbon tetrachloride, adding sufficient caustic alkali to render the mass alkaline, and separating the alkali-metal salt of benzanthronecarboxylic acid.

12. In the process of manufacturing Bzl-benzanthrone-carboxylic acid by reacting benzanthrone with carbon tetrachloride to produce a mixture of benzanthrone, benzanthrone-trichloro-methane and dibenzanthronyl-dichloro-methane, the steps which comprise neutralizing the reaction mixture with aqueous caustic soda, and filtering off a solution of the sodium salt of Bzlbenzanthrone-carboxylic acid.

13. In the process of manufacturing Bzl-benzanthrone-carboxylic acid by reacting benzanthrone with carbon tetrachloride to produce a mixture of benzanthrone, benzanthrone-trichloro-methane, and dibenzanthronyl-dichloromethane, the steps which comprise neutralizing the reaction mixture with aqueous caustic soda, filtering off a solution of the sodium salt of B21- benzanthrone-carboxylic acid, and acidifying the filtrate to precipitate Bzl-benzanthrone-carboxylic acid.

14. In the process of manufacturing Bzl-benzanthrone-carboxylic acid, the step which comprises reacting benzanthrone with carbon tetrachloride in the presence of aluminum chloride for a period of time shorter than that required for complete reaction, whereby to produce a mixin the presence of about mol of anhydrous aluminum chloride as compared to the weight of benzanthrone, at a temperature of 145 to 180 C.,

for a period notexceeding 4 hours. .1 r v- 17. The process which comprises heating solution ofbenzanthrone in carbon tetrachloride in the presence of a copper catalyst at a temperature of about ISO-165 C. and for: ajperiod' of about 18 hours.

VIKTOR. M. WEINMAYR. JOHN M. 'I'INKER. 

